WO1995009244A1 - Method of preparing arabinonucleotides - Google Patents

Abstract

Described is a method of preparing arabinonucleotides of general formula (I), in which X is a hydrogen or fluorine atom. The method is characterized in that an arabinonucleoside of general formula (II), in which X is as defined above, is fermented with a microorganism capable of phosphorylating nucleosides, the fermentation being carried out in the presence of an aryl phosphate of general formula (III), in which Y is a hydrogen atom or a nitro group and the two Z groups are both hydrogen atoms or both alkali-metal atoms.

Description

Process for the production of arabinonucleotides

The invention relates to a method for producing arabinonucleotides of the general formula I.

H OH woπn

X represents a hydrogen atom or a fluorine atom, which is characterized in that

H OH where X has the meaning given above, in the presence of an aryl phosphate of the general formula III

woπn Y is a hydrogen atom or a nitro group and

Z symbolizes two hydrogen atoms or two alkali metal atoms, fermented with a microorganism capable of phosphorylating nucleosides. The arabinonucleotides of the general formula I, the 9 (5-0-phosphono-ß-D-arabinofύranosyl) -9-H-purine-6-amine (= vidarabine phosphate) and the 2-fluoro-9- (5-0-phosphono -ß-D-arabinofuranosyl) -9H-purine-6-amine (= fludarabine phosphate) are known to be pharmacologically active substances which are distinguished by an antiviral and cylostatic activity (EP-A 317,728 and WO 9209604).

According to the known methods, these compounds are prepared by phosphorylation of the corresponding nucleosides (Bull, of th. Chem. Soc. Japan 42, 1969, 3505-3508), New Journal of Chem. 11, 1987, 779-785 and WO 9209604). In this process, heavily contaminated raw products are obtained, the purification of which is very complex and lossy.

The method according to the invention enables these substances to be synthesized in a relatively simple manner in a substantially purer form than is possible using the previously known methods.

This is surprising for the person skilled in the art. From the studies by Koji Misugi et al. (Agr.Biol.Chem. 28, 1964, 586-600) has long been known that the nucleoside inosine can be microbiologically phosphorylated, but one had to expect that the phosphorylation of the nucleosides of the general formula II would achieve significantly less favorable results would. This is particularly for two reasons: From the work of Koji Mitsugi et al. it is known that mixtures of isomeric nucleotides are often obtained in the phosphorylation of inosine. It was therefore to be expected that the phosphorylation of the nucleosides of the general formula II would result in the same, if not increased, mixtures of isomers.

It is known that adenosine is broken down in the body metabolism with deamination and oxidation (Römpps Chemie-Lexikon, 8th edition, Franckh'sche Verlagshandlung, Stuttgart (DE) 65) and it was therefore to be feared that in the microbiological conversion of the adenine derivatives of the general formula II would also at least partially degrade the compounds.

Like my own experiments, which were also carried out by Koji Mitsugi et al. mentioned microorganism Pseudomonas trifolii (IAM 1309 after an investigation by the DSM identification service is his is today classified as a pantoea agglomerate), the described feared disadvantages occur in the phosphorylation of the nucleosides general formula II, but the reaction seems to be even more favorable than that of inosine.

It is highly probable that the method according to the invention cannot be used only with the tested microorganism Pseudomonas trifolii (IAM 1309), but also with other microorganisms described by Koji Mitsugi et al. described as being suitable for phosphorylation of nucleosides. These are, for example, the microorganisms:

Pseudomonas trifolii IAM 1543 and IAM 1555

Pseudomonas perlurdia IAM 1589, IAM 1600, IAM 1610 and IAM 1627,

Pseudomonas melanogenum F-ll,

Alcaligenes visco lactis ATCC 9039 and IFM AN-14,

Achromobacter superficialis IAM 1433

Flavobacterium lactis IFM F101

Flavobacterium fuscum IAM 1181

Flavobacterium flavescens IFO 3085

Flavobacterium breve IFM S-15

Serracina marcesce s IAM 1022, IAM 1065, IAM 1067, LAM 1104, LAM

1135, IAM 1161, IAM 1205, IAM 1223, IAM 1703

and other microorganisms listed in this publication.

The process according to the invention must be carried out in the presence of a large excess of a phosphate donor in order to achieve sufficient phosphorylation of the arabinonucleosides of the general formula II, which can be prepared only with great difficulty. Suitable phosphate donors include aryl phosphates, such as phenyl phosphate or p-nitrophenyl phosphate. Usually 2-5 mol of phosphate donor is used per mol of nucleoside to be converted. Since the proteases found in bacteria are mostly alkaline proteases, which are zinc proteins and mostly require magnesium ions to develop their effectiveness, it is advisable to carry out the reaction in the presence of 0.2 to 4.0% of a water-soluble zinc salt, such as zinc sulfate dihydrate or optionally also in the presence of 0.01 to 0.3% of a water-soluble magnesium salt, such as magnesium sulfate heptahydrate.

Apart from the conditions mentioned, the process according to the invention can be carried out under the same conditions which are usually used in the fermentation of substrates with bacterial cultures. The bacterial culture is grown in a suitable medium, the substrate and the auxiliary substances are added and the culture is fermented with stirring and aeration until a maximum substrate conversion is achieved.

If this method is used, fermentation broths are generally obtained in which the process product is difficult to separate from the fermentation medium.

For this reason, it generally seems more appropriate to carry out the reaction under the conditions of the resting cell method. For this purpose, the bacterial cultures are grown in a conventional medium, the bacteria are separated by centrifugation, washed, possibly freeze-dried - in order to make them storable - resuspended in an isotonic buffer solution, mixed with substrate and auxiliary substances and fermented at 20 to 40 ° C until maximum substrate conversion is achieved. Under these circumstances, the preparation of the batch is not difficult, the cell material is centrifuged off, the supernatant is concentrated and the precipitated process product, which can be contaminated by easily separable starting material, is filtered off.

The following exemplary embodiments serve to explain the method according to the invention: example 1

a) Containing a petri dish with a medium

1% peptone

0.2% yeast extract

0.1% magnesium sulfate heptahydrate and

1.5% agar

- adjusted to pH 7.0 -

is inoculated with a dry culture of Pseudomonas trifolii LAM 1309 and incubated for 16 hours at 30 °.

b) Containing a 2 1 Erlenmeyer flask with 1 1 medium

1% peptone

0.2% yeast extract and

0.1% magnesium sulfate heptahydrate

- adjusted to pH 7 -

is inoculated by means of an eyelet with the preculture prepared according to a) and incubated for 16 hours at 30 ° C. at 180 revolutions per minute. The cells are then centrifuged at 6000 rpm for 15 minutes at 10 ° C., washed with 200 ml of a 0.02% aqueous potassium chloride solution, suspended in 20 ml of a 0.02% aqueous potassium chloride solution, frozen at -20 ° C. and freeze-dried for 20 hours. For use, the freeze-dried cells are stored at room temperature.

c) In screw-top bottles are in 0.5 M sodium acetate buffer of pH 4.5 per 1

2.0 g of 2-fluoro-9- (ß-DArabonofuranosyl) -9H-purin-6-amine,

0.12 g zinc sulfate dihydrate, 1.0 g of freeze-dried Pseudomonat trifolii IAM 1309 culture and prepared according to Example 1b

8.0 g disodium p-nitrophenyl phosphate

entered and the reaction mixtures shaken for 40 hours at 40 ° C at 60 revolutions per minute.

Then the cells are centrifuged off at 8000 revolutions per minute, the supernatant is concentrated in the ratio evaporator at a maximum of 50 ° C to 1/20 of the original volume, the separated crude product is filtered off, washed with water and dried for 24 hours at 100 ° C and lOOOOPa.

According to HPLC analysis of the crude product obtained, about 50% 2-fluoro-9- (5-0-phosphono-ß-D-arabinofuranosyl) -9Hpurin-6-amine was formed in this experiment.

Example 2

Under the conditions of Example 1c, but with the addition of 16 g / l disodium p-nitrophenyl phosphate instead of 8 g / l, 2.0 g / l 2-fluoro-9 (β-D-arabinofuranosyl) -9H-purine-6-amine 40 Shaken for hours at 40 ° C at 60 revolutions per minute. The reaction mixture is worked up as described in Example 1c and about 60% of 2-fluoro-9- (5-0-phosphono-β-D-arabinofuranosyl) -9H-purine-6-amine is obtained.

Example 3

Under the conditions of Example 1c but with the addition of 40 g / l disodium p-nitrophenyl phosphate instead of 8 g / l, 2.0 g / l of 2-fluoro-9 (β-D-arabinofuranosyl) -9H-purine-6-amine Shaken for 100 hours at 40 ° C at 60 revolutions per minute. The reaction mixture is worked up as described in Example 1c and about 85% of 2-fluoro-9- (5-0-phosphono-β-D-arabinofuranosyl) -9-H-purine-6-amine is obtained. Example 4

Under the conditions of Example 1c but with the addition of 20 g / l disodium phenyl phosphate instead of 8 g / l disodium p-nitrophenyl phosphate, 2.0 g / l 2-fluoro-9 (β-D-arabinofuranosyl) -9H-purine-6 - Shaken amine for 100 hours at 40 ° C at 60 revolutions per minute. The reaction mixture is worked up as described in Example 1c and about 50% of 2-fluoro-9- (5-0-phosphono-β-D-arabinofuranosyl) - 9H-purine-6-amine is obtained.

Example 5

Under the conditions of Example 4 but with the addition of 30 g / l disodium phenyl phosphate instead of 20 g / l, 2.0 g / l 2-fluoro-9- (β-D-arabinofuranosyl) -9H-purine-6-amine are reacted, prepared and 60% of 2-fluoro-9- (5-0-phosphono-ß-D-arabinofuranosal) -9-H-purine-6-amine is obtained.

Example 6

Under the conditions of Example 4 but with the addition of 40 g / l disodium phenyl phosphate instead of 20 g l, 2.0 g / l of 2-fluoro-9- (β-D-arabinofurynosyl) -9H-purine-6-amine are reacted and processed and 70% of 2-fluoro-9- (5-0-phosphono-ß-D-arabinofuranosyl) 9-H-purine-6-amine is obtained.

Claims

claims 1. Process for the preparation of arabinonucleotides of the general formula I

H OH woπn X represents a hydrogen atom or a fluorine atom, which is characterized in that an arabinonucleoside of the general formula II

H OH wherein X has the meaning given above, in the presence of an aryl phosphate of the general formula III

woπn Y is a hydrogen atom or a nitro group and Z symbolizes two hydrogen atoms or two alkali metal atoms, fermented with a microorganism capable of phosphorylating nucleosides. 2. A process for the preparation of arabinonucleotides of the general formula I according to claim 1, characterized in that the fermentation is carried out in the presence of a water-soluble zinc (II) salt. 3. A process for the preparation of .Arabinomicleotiden of general formula I according to claim 1 and 2, characterized in that one carries out the fermentation under the conditions of the resting cell process. 4. A process for the preparation of arabinonucleotides of the general formula I according to claims 1 to 3, characterized in that a microorganism of the species Pseudomonas trifolii is used for the fermentation. 5. A process for the preparation of arabinonucleotides of the general formula I according to claim 1 to 4, characterized in that a microorganism of the species Pseudomonas trifolii IAM 1309 is used for the fermentation.